Method and apparatus for transmitting/receiving encryption information in a mobile broadcast system

ABSTRACT

A method and apparatus for transmitting/receiving encryption information in a mobile broadcast system providing broadcast service (BCAST) are disclosed. In the mobile broadcast system, a broadcast (BCAST) Service Distribution/Adaptation (BSD/A) unit comprises a transmitter for transmitting a Registration Key Material (RKM) request message for requesting delivery of an RKM for registration of the BCAST service of a terminal to a BCAST Subscription Management (BSM) unit managing subscriber information of the terminal, and a receiver for receiving an RKM request response message from the BSM unit. The RKM request message includes an identifier (ID) of the BCAST service, and the RKM request response message includes the ID of the BCAST service and the RKM. The transmitter transmits a Long-Term Key Message (LTKM) request message for requesting delivery of an LTKM provided to the terminal during subscription of the BCAST service to the BSM unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 11/598,236, which was filed in the U.S. Patent and TrademarkOffice on Nov. 13, 2006, and claims the benefit under 35 U.S.C. §119(a)of Korean Patent Application Serial No. 10-2005-0107760, filed in theKorean Intellectual Property Office on Nov. 10, 2005, the entiredisclosures of both said prior applications being hereby incorporated byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to an encryption method andapparatus in a mobile broadcast system. More particularly, the presentinvention relates to a method and an apparatus fortransmitting/receiving encryption information for service/contentprotection in a mobile broadcast system.

2. Description of the Related Art

In general, Broadcast (BCAST) Service refers to a technology in which aserver, managing a broadcast service, broadcasts encrypted service andmultiple terminals receive the encrypted broadcast service. Each of theterminals decrypts the encrypted service provided from the server usingits own encryption key, thereby allowing the user to enjoy thecorresponding service.

The BCAST service may be a charged service. To meet the demand forcopyright protection technology for preventing illegal copying anddistribution of the service, 3rd Generation Partnership Project (3GPP)or Open Mobile Alliance (OMA), which is a standards group, hasintroduced a Digital Rights Management (DRM) technology based onflexibility and facility for Right Object (RO) of the user. However, themobile broadcast system gives no definition of an encryption method forservice protection between entities and of interfaces between theentities, so there is a need to define the encryption method.

Accordingly, there is a need for an improved apparatus and method fortransmitting/receiving encryption information in a mobile broadcastsystem.

SUMMARY OF THE INVENTION

Exemplary embodiments of the present invention address at least theabove problems and/or disadvantages and provide at least the advantagesdescribed below. Accordingly, an aspect of the present invention is toprovide a method an apparatus for transmitting/receiving encryptioninformation between entities in a mobile broadcast system.

According to one exemplary aspect of the present invention, there isprovided a method for transmitting/receiving encryption information by abroadcast (BCAST) Service Distribution/Adaptation (BSD/A) unit in amobile broadcast system providing a BCAST service. The method comprisestransmitting a Registration Key Material (RKM) request message forrequesting delivery of an RKM for registration of the BCAST service of aterminal to a BCAST Subscription Management (BSM) unit managingsubscriber information of the terminal, receiving an RKM requestresponse message from the BSM, transmitting a Long-Term Key Message(LTKM) request message for requesting delivery of an LTKM provided tothe terminal during subscription of the BCAST service to the BSM unit,receiving an LTKM request response message from the BSM unit,transmitting a Short-Term Key Message (STKM) request message foracquisition of an STKM including a Traffic Encryption Key (TEK) used fordecryption of the BCAST service by the terminal to the BSM unit, andreceiving an STKM request response message from the BSM unit. The RKMrequest message includes an identifier (ID) of the BCAST service, andthe RKM request response message includes the ID of the BCAST serviceand the RKM, the LTKM request message includes the ID of the BCASTservice, and the LTKM request response message includes the ID of theBCAST service and the LTKM, and the STKM request message includes the IDof the BCAST service, and the STKM request response message includes theID of the BCAST service and the STKM.

According to another exemplary aspect of the present invention, there isprovided a method for transmitting/receiving encryption information by abroadcast (BCAST) Subscription Management (BSM) unit in a mobilebroadcast system providing a BCAST service. The method comprisesreceiving a Registration Key Material (RKM) request message forrequesting delivery of an RKM for registration of the BCAST service of aterminal, from a BCAST Service Distribution/Adaptation (BSD/A) unit,transmitting an RKM request response message to the BSD/A, receiving aLong-Term Key Message (LTKM) request message for requesting delivery ofan LTKM provided to the terminal during subscription of the BCASTservice, from the BSD/A unit, transmitting an LTKM request responsemessage to the BSD/A unit, receiving a Short-Term Key Message (STKM)request message for acquisition of an STKM including a TrafficEncryption Key (TEK) used for decryption of the BCAST service by theterminal, from the BSD/A unit, and transmitting an STKM request responsemessage to the BSD/A. The RKM request message includes an identifier(ID) of the BCAST service, and the RKM request response message includesthe ID of the BCAST service and the RKM, the LTKM request messageincludes the ID of the BCAST service, and the LTKM request responsemessage includes the ID of the BCAST service and the LTKM, and the STKMrequest message includes the ID of the BCAST service, and the STKMrequest response message includes the ID of the BCAST service and theSTKM.

According to further another exemplary aspect of the present invention,there is provided a method for transmitting/receiving encryptioninformation by a broadcast (BCAST) Subscription Management (BSM) unit ina mobile broadcast system providing a BCAST service. The methodcomprises transmitting a Registration Key Material (RKM) deliverymessage for delivery of an RKM for registration of the BCAST service ofa terminal to a BCAST Service Distribution/Adaptation (BSD/A) unit,receiving an RKM delivery confirmation message indicatingsuccess/failure in receipt of the RKM delivery message, from the BSD/Aunit, transmitting a Long-Term Key Message (LTKM) delivery message fordelivery an LTKM provided to the terminal during subscription of theBCAST service to the BSD/A unit, receiving an LTKM delivery confirmationmessage indicating success/failure in receipt of the RKM deliverymessage from the BSD/A unit, transmitting a Short-Term Key Message(STKM) delivery message for delivery an STKM including a TrafficEncryption Key (TEK) used for decryption of the BCAST service by theterminal to the BSD/A unit, and receiving an STKM delivery confirmationmessage indicating success/failure in receipt of the STKM deliverymessage from the BSD/A unit. The RKM request message includes anidentifier (ID) of the BCAST service, and the RKM request responsemessage includes the ID of the BCAST service and the RKM, the LTKMrequest message includes the ID of the BCAST service, and the LTKMrequest response message includes the ID of the BCAST service and theLTKM, and the STKM request message includes the ID of the BCAST service,and the STKM request response message includes the ID of the BCASTservice and the STKM.

According to yet another exemplary aspect of the present invention,there is provided a method for transmitting/receiving encryptioninformation by a broadcast (BCAST) Subscription Management (BSM) unit ina mobile broadcast system providing a BCAST service. The methodcomprises transmitting a Registration Key Material (RKM) deliverymessage for delivery of an RKM for registration of the BCAST service ofa terminal to a BCAST Service Distribution/Adaptation (BSD/A) unit,receiving an RKM delivery confirmation message indicatingsuccess/failure in receipt of the RKM delivery message, from the BSD/Aunit, transmitting a Long-Term Key Message (LTKM) delivery message fordelivery an LTKM provided to the terminal during subscription of theBCAST service to the BSD/A unit, receiving an LTKM delivery confirmationmessage indicating success/failure in receipt of the RKM deliverymessage from the BSD/A unit, transmitting a Short-Term Key Message(STKM) delivery message for delivery an STKM including a TrafficEncryption Key (TEK) used for decryption of the BCAST service by theterminal to the BSD/A unit, and receiving an STKM delivery confirmationmessage indicating success/failure in receipt of the STKM deliverymessage from the BSD/A unit. The RKM delivery message includes anidentifier (ID) of the BCAST service and the RKM, and the RKM deliveryconfirmation message includes the ID of the BCAST service, the LTKMdelivery message includes the ID of the BCAST service and the LTKM, andthe LTKM delivery confirmation message includes the ID of the BCASTservice, and the STKM delivery message includes the ID of the BCASTservice and the STKM, and the STKM delivery confirmation messageincludes the ID of the BCAST service.

According to one exemplary aspect of the present invention, there isprovided a broadcast (BCAST) Service Distribution/Adaptation (BSD/A)unit in a mobile broadcast system providing a BCAST. The BSD/A unitcomprises transmitter for transmitting a Registration Key Material (RKM)request message for requesting delivery of an RKM for registration ofthe BCAST service of a terminal to a BCAST Subscription Management (BSM)unit managing subscriber information of the terminal, and a receiver forreceiving an RKM request response message from the BSM unit. The RKMrequest message includes an identifier (ID) of the BCAST service, andthe RKM request response message includes the ID of the BCAST serviceand the RKM, the transmitter transmits a Long-Term Key Message (LTKM)request message for requesting delivery of an LTKM provided to theterminal during subscription of the BCAST service to the BSM unit, thereceiver receives an LTKM request response message from the BSM unit,the LTKM request message includes the ID of the BCAST service, and theLTKM request response message includes the ID of the BCAST service andthe LTKM, the transmitter transmits a Short-Term Key Message (STKM)request message for acquisition of an STKM including a TrafficEncryption Key (TEK) used for decryption of the BCAST service by theterminal to the BSM unit, the receiver receives an STKM request responsemessage from the BSM unit, and the STKM request message includes the IDof the BCAST service, and the STKM request response message includes theID of the BCAST service and the STKM.

According to another exemplary aspect of the present invention, there isprovided a broadcast (BCAST) Subscription Management (BSM) unit in amobile broadcast system providing a BCAST service. The BSM unitcomprises a receiver for receiving a Registration Key Material (RKM)request message for requesting delivery of an RKM for registration of aBCAST service of a terminal, from a BCAST ServiceDistribution/Adaptation (BSD/A) unit, and a transmitter for transmittingan RKM request response message to the BSD/A. The RKM request messageincludes an identifier (ID) of the BCAST service, and the RKM requestresponse message includes the ID of the BCAST service and the RKM, thereceiver receives a Long-Term Key Message (LTKM) request message forrequesting delivery of an LTKM provided to the terminal duringsubscription of the BCAST service, from the BSD/A unit, the transmittertransmits an LTKM request response message to the BSD/A unit, the LTKMrequest message includes the ID of the BCAST service, and the LTKMrequest response message includes the ID of the BCAST service and theLTKM, the receiver receives a Short-Term Key Message (STKM) requestmessage for acquisition of an STKM including a Traffic Encryption Key(TEK) used for decryption of the BCAST service by the terminal, from theBSD/A unit, the transmitter transmits an STKM request response messageto the BSD/A unit, and the STKM request message includes the ID of theBCAST service, and the STKM request response message includes the ID ofthe BCAST service and the STKM.

According to further another exemplary aspect of the present invention,there is provided a broadcast (BCAST) Subscription Management (BSM) unitin a mobile broadcast system providing a BCAST service. The BSM unitcomprises a transmitter for transmitting a Registration Key Material(RKM) delivery message for delivery of an RKM for registration of theBCAST service of a terminal to a BCAST Service Distribution/Adaptation(BSD/A) unit, and a receiver for receiving an RKM delivery confirmationmessage indicating success/failure in receipt of the RKM deliverymessage from the BSD/A unit. The RKM delivery message includes anidentifier (ID) of the BCAST service and the RKM, and the RKM deliveryconfirmation message includes the ID of the BCAST service, thetransmitter transmits a Long-Term Key Message (LTKM) delivery messagefor delivery an LTKM provided to the terminal during subscription ofBCAST service to the BSD/A unit, the receiver receives an LTKM deliveryconfirmation message indicating success/failure in receipt of the LTKMdelivery message, from the BSD/A unit, the LTKM delivery messageincludes the ID of the BCAST service and the LTKM, and the LTKM deliveryconfirmation message includes the ID of the BCAST service, thetransmitter transmits a Short-Term Key Message (STKM) delivery messagefor delivery an STKM including a Traffic Encryption Key (TEK) used fordecryption of the BCAST service by the terminal to the BSD/A unit, thereceiver receives an STKM delivery confirmation message indicatingsuccess/failure in receipt of the STKM delivery message from the BSD/Aunit, and the STKM delivery message includes the ID of the BCAST serviceand the STKM, and the STKM delivery confirmation message includes the IDof the BCAST service.

According to yet another exemplary aspect of the present invention,there is provided a broadcast (BCAST) Service Distribution/Adaptation(BSD/A) unit in a mobile broadcast system providing a BCAST service. TheBSD/A unit comprises a receiver for receiving a Registration KeyMaterial (RKM) delivery message for delivery of an RKM for registrationof the BCAST service of a terminal, from a BCAST Subscription Management(BSM) unit, and a transmitter for transmitting an RKM deliveryconfirmation message indicating success/failure in receipt of the RKMdelivery message, to the BSM unit. The RKM delivery message includes anidentifier (ID) of the BCAST service, and the RKM, and the RKM deliveryconfirmation message includes the ID of the BCAST service, the receiverreceives a Long-Term Key Message (LTKM) delivery message for delivery anLTKM provided to the terminal during subscription of BCAST service, fromthe BSM unit, wherein the transmitter transmits an LTKM deliveryconfirmation message indicating success/failure in receipt of the LTKMdelivery message, to the BSM unit, the LTKM delivery message includesthe ID of the BCAST service and the LTKM, and the LTKM deliveryconfirmation message includes the ID of the BCAST service, the receiverreceives a Short-Term Key Message (STKM) delivery message for deliveryan STKM including a Traffic Encryption Key (TEK) used for decryption ofthe BCAST service by the terminal, from the BSM unit, the transmittertransmits an STKM delivery confirmation message indicatingsuccess/failure in receipt of the STKM delivery message to the BSM unit,and the STKM delivery message includes the ID of the BCAST service andthe STKM, and the STKM delivery confirmation message includes the ID ofthe BCAST service.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will become more apparent from the following detaileddescription when taken in conjunction with the accompanying drawings inwhich:

FIG. 1 is a signaling diagram illustrating a signal flow of encryptioninformation in a mobile broadcast system according to an exemplaryembodiment of the present invention;

FIGS. 2A and 2B are diagrams illustrating an information flow betweenentities of a server according to an exemplary embodiment of the presentinvention, for Service Protection and Content Protection, respectively;

FIGS. 3A and 3B are diagrams illustrating an interfacing method betweena BSA and a BSM for Content Protection according to an exemplaryembodiment of the present invention;

FIG. 4 is a diagram illustrating a protocol stack constituting aninterface between a BSA and a BSM according to an exemplary embodimentof the present invention;

FIGS. 5A and 5B are diagrams illustrating a method for acquiring TEK bya BSD/A for Service Protection according to an exemplary embodiment ofthe present invention;

FIG. 6 is a diagram illustrating a protocol stack for an interfacebetween a BSD/A and a BSM for Service Protection according to anexemplary embodiment of the present invention;

FIGS. 7A and 7B are diagrams illustrating a method for acquiring STKM bya BSD/A according to an exemplary embodiment of the present invention;

FIGS. 8A and 8B are diagrams illustrating a method for acquiring LTKM bya BSD/A according to an exemplary embodiment of the present invention;

FIGS. 9A and 9B are diagrams illustrating a method for acquiring RKM bya BSD/A for Service Protection and Content Protection according to anexemplary embodiment of the present invention;

FIG. 10 is a diagram illustrating a protocol stack for an interfacebetween a BSD/A and a BSM for Service Protection according to anexemplary embodiment of the present invention;

FIG. 11 is a diagram illustrating a protocol stack for an interfacebetween a BSD/A and a BSM for Content Protection according to anexemplary embodiment of the present invention; and

FIG. 12 is a diagram illustrating a Terminal in a mobile broadcastsystem according to an exemplary embodiment of the present invention.

FIG. 13 is a block diagram of a BSD/A according to an exemplaryembodiment of the present invention.

FIG. 14 is a block diagram of the BSM according to an exemplaryembodiment of the present invention.

Throughout the drawings, the same drawing reference numerals will beunderstood to refer to the same elements, features, and structures.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The matters defined in the description such as a detailed constructionand elements are provided to assist in a comprehensive understanding ofthe embodiments of the invention and are merely exemplary. Accordingly,those of ordinary skill in the art will recognize that various changesand modifications of the embodiments described herein can be madewithout departing from the scope and spirit of the invention. Also,descriptions of well-known functions and constructions are omitted forclarity and conciseness. Exemplary embodiments of the present inventionwill now be described in detail with reference to the drawings.

In the following detailed description, exemplary embodiments of thepresent invention for achieving the above and other objects will bepresented. Although names of the entities defined in 3rd GenerationPartnership Project (3GPP) which is the asynchronous mobilecommunication standard, or Open Mobile Alliance (OMA) which is theterminal application standard, will be used for convenience, thestandards and names should not limit the scope of the present invention,and the present invention can be applied to the systems having a similartechnical background.

The present invention proposes a method and an apparatus for protectinga broadcast service. Specifically, the present invention proposes astructure for service protection and a function of each entity in thebroadcast network. To this end, the present invention stably delivers aservice broadcasted to a terminal according to structure and function ofeach entity, including the terminal, thereby allowing the terminal toreproduce the service.

An exemplary mobile broadcast system and a message flow therein will nowbe described in detail with reference to FIG. 1.

FIG. 1 is a signaling diagram illustrating a signal flow of encryptioninformation in a mobile broadcast system according to an exemplaryembodiment of the present invention.

A function of each entity in FIG. 1 will first be described. A ContentCreation (CC) 10 is a provider of Broadcast Service (BCAST) service. TheBCAST service can include audio/video broadcast service, music/data filedownload service, and the like.

A BCAST Service Application (BSA) 20 processes data of the BCAST serviceprovided from the Content Creation 10 in a form appropriate for theBCAST network, generates BCAST service data, and generates standardizedmetadata necessary for mobile broadcast guide.

A BCAST Service Distribution/Adaptation (BSD/A) unit (hereafter “BSD/A”)30 establishes a carrier over which it will transmit the BCAST servicedata provided from the BSA 20, determines a delivery schedule of theBCAST service, and generates a mobile broadcast guide.

A BCAST Subscription Management (BSM) unit (hereafter “BSM”) 40 managessubscription information and service provisioning information forreception of the BCAST service, and information on an apparatus forreceiving the BCAST service.

A Terminal 50 is a terminal capable of receiving the BCAST service, andcan be connected to a cellular network according to terminal capability.It will be assumed herein that the Terminal 50 is a terminal that can beconnected to the cellular network.

A description will now be made of Content Protection and ServiceProtection according to an exemplary embodiment of the presentinvention. The Content Protection protects the broadcasted files andstreams. Rights Management for contents is performed by a terminal. Theprotected contents are encrypted by the BSA 20 and then broadcast to aTerminal 50. The Service Protection protects the broadcasted files andstreams, and encryption on the contents is performed by the BSD/A 30.The Content Protection is similar to the Service Protection in terms ofprotecting the contents. However, unlike the Service Protection, theContent Protection differs according to use/nonuse of DRM. That is, theContent Protection includes a function of managing a valid interval ofthe contents that the terminal has received, and possibility of copyingthe contents. For the Content Protection, the contents are encrypted bythe BSA 20 and then broadcast to a Terminal 50.

For both the Service Protection and the Content Protection, the BSM 40performs subscription management on the terminal. As the broadcastservice is delivered to the Terminal 50 through the entities for eachfunction, a user of Terminal 50 can enjoy the service. Herein, a messagerelated to the Service Protection and the Content Protection will becalled ‘encryption information’.

An exemplary method for delivering an encryption information messagewill now be described with reference to FIG. 1. In order to use thebroadcasted service and contents, a Terminal 50 should register in theBSM 40 and then receive a Registration Key Material (RKM) in step 100.Thereafter, if the Terminal 50 subscribes to a particular broadcastservice, it should acquire a Long-Term Key Message (LTKM) in step 110.In addition, the Terminal 50 should acquire a Short-Term Key Message(STKM) used for actually decrypting the encrypted service and contentsin step 120. The Terminal 50 can decrypt the LTKM using the RKM, and candecrypt the STKM using a Service Encryption Key (SEK) obtained as aresult of the decryption. The STKM includes a Traffic Encryption Key(TEK), and the Terminal 50 can actually decrypt the encrypted serviceand contents using the TEK. It is shown in FIG. 1 that the encryptioninformation messages such as RKM, LTKM and STKM are delivered from theBSD/A 30 to the Terminal 50 over a broadcast channel. A Terminal 50capable of using an interaction channel, although not shown in FIG. 1,can alternatively receive the RKM and the LTKM through directcommunication with the BSM 40.

A description will now be made of elements of exemplary messages usedfor delivery of encryption information.

Table 1 to Table 6 below show schema tables of the messages describedabove, and show in regular sequence definitions of the message formatsused in exemplary embodiments of the present invention, and adescription of each field is specified in the tables.

TABLE 1 Request Message Format Req-1 Cate- Cardi- Data Name Type gorynality Description Type Tag E M 1 Type of message Integer Version E O 1Version of standard Integer supported by this message Message ID E M 1ID of this message String Destination E M 1 Message destination IDString Source E M 1 Message source ID String Service/ E M 1 Associatedinformation String Content Info. such as Service/content ID Time E O 1Message-delivered Time String

TABLE 2 Response Message Format Res-1 Cate- Cardi- Data Name Type gorynality Description Type Tag E M 1 Type of message Integer Version E O 1Version of standard Integer supported by this message Message ID E M 1ID of request message String Destination E M 1 Message destination IDString Source E M 1 Message source ID String Service/ E O 1 Associatedinformation String Content Info. such as Service/content ID Status E M 1Response result of Integer message Data E O 1 Information intendedBinary to be delivered to destination Time E O 1 Message-delivered timeString

TABLE 3 Response Message Format Res-2 Cate- Cardi- Data Name Type gorynality Description Type Tag E M 1 Type of message Integer Message ID E M1 ID of request message String Status E M 1 Response result of Integermessage Data E O 1 Information intended Binary to be delivered todestination

TABLE 4 Delivery Message Format Tra-1 Cate- Cardi- Data Name Type gorynality Description Type Tag E M 1 Type of message Integer Version E O 1Version of standard Integer supported by this message Target E M 1Target terminal of String Terminal this message Message ID E M 1 ID ofthis message String Destination E M 1 Message destination ID StringSource E M 1 Message source ID String Service/ E M 1 Associatedinformation String Content Info. such as Service/content ID Data E M 1Information intended Binary to be delivered to destination Time E O 1Message-delivered time String

TABLE 5 Confirm Message Format Con-1 Cate- Cardi- Data Name Type gorynality Description Type Tag E M 1 Type of message Integer Version E O 1Version of standard Integer supported by this message Message ID E M 1ID of delivery message String Destination E M 1 Message destination IDString Source E M 1 Message source ID String Service/ E O 1 Associatedinformation String Content Info. such as Service/content ID Status E M 1Confirmation result of Integer message Time E O 1 Message-delivered timeString

TABLE 6 Confirm Message Format Con-2 Cate- Cardi- Data Name Type gorynality Description Type Tag E M 1 Type of message Integer Message ID E M1 ID of delivery message String Status E M 1 Confirmation result ofInteger message

In the tables, ‘Name’ indicates names of elements and attributesconstituting the corresponding message. ‘Type’ indicates whether thecorresponding name corresponds to the type of an element or anattribute. Each element has values of E1, E2, E3 and E4. E1 means anupper element for the whole message, E2 indicates a sub-element of E1,E3 indicates a sub-element of E2, and E4 indicates a sub-element of E3.The attribute is indicated by A, and A indicates an attribute of thecorresponding element. For example, A under E1 indicates an attribute ofE1. ‘Category’ is used for indicating whether a corresponding element orattribute is mandatory, and has a value M if the value is mandatory, anda value O if the value is optional. ‘Cardinality’ indicates relationsbetween the elements, and has values of {0, 0.1, 1, 0 . . . n, 1 . . .n}, where “0” means an optional relation, “1” means a mandatoryrelation, and ‘n’ means the possibility of having a plurality of values.For example, ‘0 . . . n’ means the possibility that there is nocorresponding element or there are n corresponding elements.‘Description’ defines the meaning of the corresponding element orattribute. ‘Data Type’ indicates a data type of the correspondingelement or attribute.

In Table 7 below, the type of each message is distinguished using Tagused in the message formats defined in Table 1 to Table 6. However, theTag values defined herein simply distinguish the message types, and arenot always fixed, but subject to change according to circumstances.

In the Response Message and the Confirm Message, Status=‘0’ indicatesthat the Request and Delivery Messages were successfully received andthe associated item was performed, and Status=‘1’ indicates thatreception of the Request and Delivery Messages was failed and executionof the associated item was failed.

Each message can obtain improvement in performance using Res-2 or Con-2,which is a shortened message provided using Message ID as shown in‘Applied Message Format’ of Table 7 below.

TABLE 7 Message Type and Applied Message Format Based on Tag AppliedDelivery Tag Message Type Message Format Info. 1 TEK Request MessageReq-1 TEK 2 TEK Request Response Message Res-1 or Res-2 3 TEK DeliveryMessage Tra-1 4 TEK Delivery Confirm Message Con-1 or Con-2 5 STKMRequest Message Req-1 STKM 6 STKM Request Response Message Res-1 orRes-2 7 STKM Delivery Message Tra-1 8 STKM Delivery Confirm MessageCon-1 or Con-2 9 LTKM Request Message Req-1 LTKM 10 LTKM RequestResponse Message Res-1 or Res-2 11 LTKM Delivery Message Tra-1 12 LTKMDelivery Confirm Message Con-1 or Con-2 13 RKM Request Message Req-1 RKM14 RKM Request Response Message Res-1 or Res-2 15 RKM Delivery MessageTra-1 16 RKM Delivery Confirm Message Con-1 or Con-2

Exemplary embodiments of the present invention provide a method forexchanging encryption information such as TEK, STKM, LTKM and RKMrelated to the Service Protection and Content Protection between the BSA20 and the BSM 40, and between the BSD/A 30 and the BSM 40. FIGS. 2A and2B show the information exchanged between entities, and the detailedexamples will be described with reference to the accompanying drawings.

FIGS. 2A and 2B are diagrams illustrating an information flow betweenentities of a server according to an exemplary embodiment of the presentinvention, for Service Protection and Content Protection, respectively.Referring to FIGS. 2A and 2B, an entity for performing the ServiceProtection includes a Service Protection-Encryption (SP-E) 31 and aService Protection-Key Distribution (SP-KD) 32 in the BSD/A 30. The SP-E31 serves to encrypt the service, and the SP-KD 32 serves to transmitthe associated encryption key information up to a Terminal 50 over abroadcast channel. The BSM 40, including a Service Protection-Management(SP-M) 41 therein, manages subscription of the terminal and generationof the encryption key.

For the Content Protection, a File Distribution (FD) 33 in the BSD/A 30receives the encryption key information delivered from the BSM 40 anddelivers the received encryption key information to a terminal over abroadcast channel. The BSM 40, including a Content Protection-Management(CP-M) 42 therein, manages subscription of the terminal and generationof the encryption key. The BSA 20, including a ContentProtection-Encryption (CP-E) 21 therein, manages encryption of thecontents.

FIGS. 3A and 3B are diagrams illustrating an interfacing method betweena BSA 20 and a BSM 40 for Content Protection according to an exemplaryembodiment of the present invention, and the information transmitted forthe Content Protection will be described. In an exemplary ContentProtection method, because encryption is performed in the BSA 20, theencryption key generated by the BSM 40 is delivered to the BSA 20.Because the key used for encrypting the contents in the mobile broadcastsystem is TEK, the TEK generated by the BSM 40 should be delivered tothe BSA 20.

As shown in FIG. 3A, an exemplary delivery method starts with a TEKRequest Message transmitted from the BSA 20 in step 300, and Tagindicating the TEK Request Message is set to ‘1’. A Destination fieldindicates the BSM 40 and a Source field indicates the BSA 20. Uponreceipt of the TEK Request Message, the CP-M 42 in the BSM 40 transmitsa TEK Request Response Message with Tag=‘2’ in step 310. If a Statusfield of the Response is set to ‘0’, TEK is stored in a Data fieldbefore being transmitted, and if the TEK is not transmitted, the Statusfield is set to ‘1’ before being transmitted.

In the method of FIG. 3B, the BSM 40 transmits TEK without a requestfrom the BSA 20. In an exemplary embodiment, the CP-M 42 in the BSM 40transmits a TEK Delivery Message with Tag=‘3’ having TEK included in aData field to the CP-E 21 in the BSA 20 in step 320. In response, theBSA 20 transmits a TEK Delivery Confirm Message with Tag=‘4’ to the BSM40 in step 330. In an exemplary embodiment, a Status field is set to ‘0’indicating normal receipt of TEK. If reception of the TEK is failed, theStatus field is set to ‘1’.

FIG. 4 illustrates a protocol stack constituting an interface between aBSA 20 and a BSM 40 according to an exemplary embodiment of the presentinvention. Referring to FIG. 4, the BSA 20 and the BSM 40 can exchangedata by achieving compatibility with each other using a protocol. Datadelivery protection between the BSA 20 and the BSM 40 can realize dataprotection without restriction of protocol and data of an upper layerusing IPSec. TCP protocol and HTTP/HTTPS exist as an IPSec upper layer,and the CP-E 21 in the BSA 20 and the CP-M 42 in the BSM 40 existthereon for message exchange and an associated operation for theinterface.

FIGS. 5A and 5B illustrate a TEK acquisition method in which a BSD/A 30encrypts and broadcasts a service for Service Protection according to anexemplary embodiment of the present invention.

Referring to FIG. 5A, the SP-E 31 in the BSD/A 30 transmits a TEKRequest Message to the BSM 40 in step 400. The TEK Request Message has aTag value ‘1’, and its Destination and Source indicate the BSM 40 andthe BSD/A 30, respectively. In response to the TEK Request Message, theBSM 40 transmits a TEK Request Response Message with Tag=‘2’ in step410. The BSM 40 sets a Status value to ‘0’ when it transmits therequested TEK. Otherwise, the BSM 40 sets the Status value to ‘1’. Whenthe Status value is set to ‘0’, TEK is stored in a Data field of the TEKRequest Response Message.

In an exemplary embodiment shown in FIG. 5B, the BSM 40 directlytransmits TEK without a request from the BSD/A 30. Referring to FIG. 5B,the SP-M 41 in the BSM 40 transmits a TEK Delivery Message with Tag=‘3’having TEK included therein to the BSD/A 30 in step 420. In response,the BSD/A 30 transmits a TEK Delivery Confirm Message with Tag=‘4’ tothe BSM 40 in step 430. If the BSD/A 30 has succeeded in receiving theTEK, it sets a Status value of the TEK Delivery Confirm Message to ‘0’.However, if the BSD/A 30 has failed in receiving the TEK, it sets theStatus value ‘1’.

FIG. 6 is a diagram illustrating a protocol stack for an interfacebetween a BSD/A 30 and a BSM 40 for Service Protection according to anexemplary embodiment of the present invention. Safety between interfacesis protected using IPSec, and a protocol related to a service protectionmethod is transmitted through TCP and HTTP/HTTPS. Encryption informationtransmitted from the BSM 40 is managed by the BSD/A 30, and theencryption information includes RKM, LTKM, STKM and TEK.

FIGS. 7A and 7B are diagrams illustrating a method for acquiring STKM bythe BSD/A 30 according to an exemplary embodiment of the presentinvention. This exemplary method can be applied for Service and/orContent Protection. The STKM is an encryption key with which a terminalcan decrypt the service or contents encrypted by the BSD/A 30. The STKMcan be delivered from the BSM 40 to a Terminal 50 over an interactionchannel. However, in the broadcast channel environment, the STKM shouldbe delivered from the BSD/A 30 to a Terminal 50 over a broadcastchannel.

Referring to FIG. 7A, the BSD/A 30 transmits an STKM Request Message tothe BSM 40 in step 500. In the BSM 40, an entity for processing themessage can be the SP-M 41 for Service Protection and/or the CP-M 42 forContent Protection. The STKM Request Message has a Tag value ‘5’, andits Destination and Source indicate the BSM 40 and the BSD/A 30,respectively. In response to the STKM Request Message, the BSM 40transmits an STKM Request Response Message with Tag=‘6’ in step 510.When the BSM 40 transmits the requested STKM, it sets a Status value to‘0’ and a Data field to STKM. Otherwise, when the BSM 40 cannot transmitthe STKM, it sets the Status value to ‘1’.

In an exemplary embodiment shown in FIG. 7B, the BSM 40 directlytransmits STKM without a request from the BSD/A 30. The BSM 40 transmitsan STKM Delivery Message with Tag=‘7’ having STKM included therein tothe BSD/A 30 in step 520. In response, the BSD/A 30 transmits an STKMDelivery Confirm Message with Tag=‘8’ to the BSM 40 in step 530. If theBSD/A 30 has succeeded in receiving the STKM, it sets a Status value ofthe STKM Delivery Confirm Message to ‘0’. However, if the BSD/A 30 hasfailed in receiving the STKM, it sets the Status value ‘1’.

For Service Protection, this process is managed by the SP-KD 32 in theBSD/A 30 and the SP-M 41 in the BSM 40. For Content Protection, thisprocess is managed by the FD 33 in the BSD/A 30 and the CP-M 42 in theBSM 40.

FIGS. 8A and 8B are diagrams illustrating a method for acquiring LTKM bya BSD/A 30 according to an exemplary embodiment of the presentinvention. In the service/content protection method, LTKM information isexchanged using a broadcast channel. The LTKM can be delivered from theBSM 40 to the Terminal 50 over an interaction channel. However, in thebroadcast channel environment, the LTKM should be delivered from theBSD/A 30 to a Terminal 50 over the broadcast channel.

Referring to FIG. 8A, the BSD/A 30 transmits an LTKM Request Message tothe BSM 40 in step 600. The LTKM Request Message has a Tag value ‘9’,and its Destination and Source indicate the BSM 40 and the BSD/A 30,respectively. In response to the LTKM Request Message, the BSM 40transmits an LTKM Request Response Message with Tag=‘10’ in step 610.When the BSM 40 intends to transmit the requested LTKM, it sets a Statusvalue to ‘0’. Otherwise, the BSM 40 sets the Status value to ‘1’. Whenthe Status value is set to ‘0’, LTKM is stored in a Data field. When theStatus value is set to ‘1’, the LTKM Request Response Message istransmitted without the Data field.

In the case of FIG. 8B, the BSM 40 directly transmits LTKM without aresponse from the BSD/A 30. In this case, the BSM 40 transmits an LTKMDelivery Message with Tag=‘11’ having LTKM included therein to the BSD/A30 in step 620. In response, the BSD/A 30 transmits an LTKM DeliveryConfirm Message with Tag=‘12’ to the BSM 40 in step 630. If the BSD/A 30has succeeded in receiving the LTKM, it sets a Status value of the LTKMDelivery Confirm Message to ‘0’. However, if the BSD/A 30 has failed inreceiving the LTKM, it sets the Status value to ‘1’.

For Service Protection, this process is managed by the SP-KD 32 in theBSD/A 30 and the SP-M 41 in the BSM 40. For Content Protection, thisprocess is managed by the FD 33 in the BSD/A 30 and the CP-M 42 in theBSM 40.

FIGS. 9A and 9B are diagrams illustrating a method for acquiring RKM bya BSD/A 30 for Service Protection and Content Protection according to anexemplary embodiment of the present invention.

RKM can be delivered from the BSM 40 to the Terminal 50 over aninteraction channel. However, in the broadcast channel environment, theRKM should be delivered from the BSM 40 to the Terminal 50 over thebroadcast channel.

Referring to FIG. 9A, the BSD/A 30 transmits an RKM Request Message tothe BSM 40 in step 700. The RKM Request Message has a Tag value ‘13, andits Destination and Source indicate the BSM 40 and the BSD/A 30,respectively. In response to the RKM Request Message, the BSM 40transmits an RKM Request Response Message with Tag=‘14’ to the BSD/A 30in step 710. When the BSM 40 intends to transmit the requested RKM, itsets a Status value to ‘0’. Otherwise, the BSM 40 sets the Status valueto ‘1’. If the Status value is set to ‘0’, RKM is stored in a Data fieldbefore being transmitted. However, if the Status value is set to ‘1’,the RKM Request Response Message is transmitted without the Data field.

In the case of FIG. 9B, the BSM 40 directly transmits RKM without arequest from the BSD/A 30. In an exemplary embodiment, the BSM 40transmits an RKM Delivery Message with Tag=‘15’ having RKM includedtherein to the BSD/A 30 in step 720. In response, the BSD/A 30 transmitsan RKM Delivery Confirm Message with Tag=‘16’ to the BSM 40 in step 730.If the BSD/A 30 has succeeded in receiving the RKM, it sets a Statusvalue of the RKM Delivery Confirm Message to ‘0’. However, if the BSD/A30 has failed in receiving the RKM, it sets the Status value to ‘1’.

For Service Protection, this process is managed by the SP-KD 32 in theBSD/A 30 and the SP-M 41 in the BSM 40. For Content Protection, thisprocess is managed by the FD 33 in the BSD/A 30 and the CP-M 42 in theBSM 40.

FIG. 10 illustrates a protocol stack for an interface between a BSD/A 30and a BSM 40 for Service Protection according to an exemplary embodimentof the present invention. Safety between interfaces is protected usingIPSec, and a protocol related to a service protection method istransmitted through TCP and HTTP/HTTPS. Associated encryptioninformation includes TEK, STKM, LTKM and RKM.

FIG. 11 illustrates a protocol stack for an interface between a BSD/A 30and a BSM 40 for Content Protection according to an exemplary embodimentof the present invention. Safety between interfaces is protected usingIPSec, and a protocol related to a content protection method istransmitted through TCP and HTTP/HTTPS. Associated encryptioninformation includes STKM, LTKM and RKM.

With reference to FIG. 12, a description will now be made of a Terminal50 according to an exemplary embodiment of the present invention.

As illustrated in FIG. 12, a Terminal 50 according to an exemplaryembodiment of the present invention comprises an Application module1200, a DRM module 1210, an Authentication module 1235, a Secure Storagemodule 1260, a Communication module 1265, and a User Identity ModuleInterface (UIM I/F) module 1270.

Specifically, the Application module 1200, which may be a module likeMedia Player™, serves to reproduce decrypted contents provided from theDRM module 1210, and the DRM module 1210 serves to manage registration,service subscription, and content use.

The DRM module 1210 may include a DRM Management module 1213, aRegistration module 1215, a Rights Management module 1220, a Key StreamManagement module 1225, and a Content Decryption module 1230. Of themodules, the Registration module 1215 performs a registration operation,and the Rights Management module 1220 manages analysis and use of theRights information acquired during service subscription. The Key StreamManagement module 1225 performs an operation of decrypting the encryptedtraffic key with a service key, and the Content Decryption module 1230performs an operation of decrypting the encrypted contents with atraffic key. The entire operation of the DRM-related modules isperformed under the control of the DRM Management module 1213.

The Authentication module 1235 manages authentication protocol executionwith a user identification module and a network, for example, a serviceprovider, and performs message generation and verification using itslower module. The Authentication module 1235 may include anAuthentication Manager 1240 for taking charge of the overall protocolexecution and managing an authentication function, an EncryptionDecryption module 1245 for performing an encryption/decryption operationwith its lower module, a Digital Signature module 1250 for managingelectronic signature, and a MAC module 1255 for performing a MACoperation.

Specifically, the DRM module 1210 and the Authentication module 1235acquire a group key by verifying the Registration Response Messagereceived from the BSM 40 according to an exemplary embodiment of thepresent invention, and acquire Rights information from the ServiceSubscription Response Message received from the BSM 40 using the groupkey. In addition, upon receipt of a Traffic Key Message from the BSD/A30, the DRM module 1210 and the Authentication module 1235 acquire atraffic key using the Rights information, and decrypt the encryptedservice transmitted from the BSD/A 30 using the acquired traffic key.

The Communication module 1265, in charge of communication with anetwork, receives a message from the network and transmits a responsemessage associated in response to the received message. Specifically,the Communication module 1265 receives a message from the BSD/A 30 overa broadcast channel according to an embodiment of the present invention.According to another exemplary embodiment of the present invention, theCommunication module 1265 exchanges messages with the BSM 40 over aninteraction channel, and receives the Traffic Key Message and theencrypted service from the BSD/A 30.

The Secure Storage module 1260 stores encryption keys, and the UIM OFmodule 1270 takes charge of communication with a User Identity Module(UIM) (not shown).

As can be understood from the foregoing description, the presentinvention provides interfaces for transmitting encryption informationbetween entities, thereby providing reliable Service/Content Protectionfor broadcast service.

Hereinafter, an internal configuration of the BSD/A 30 and the BSM 40accordin to an embodiment of the present invention will be describedwith reference to FIGS. 13 and 14.

FIG. 13 is a block diagram of a BSD/A according to an exemplaryembodiment of the present invention.

Referring to FIG. 13, the BSD/A may include a controller 1300, atransmitter 1302, and a receiver 1304.

The controller 1300 controls the transmitter 1302 and the receiver 1304to perform the above-described operations of the BSD/A, which are shownin FIGS. 3A and 3B, 5A and 5B, 7A and 7B, 8A and 8B, and 9A and 9B.

For example, the transmitter 1302 and the receiver 1304 perform theprocesses of acquiring an RKM, an LTKM, and an STKM as shown in FIGS.7A, 8A, and 9A under the control of the controller 1300.

The transmitter 1302 transmits an RKM request message for requestingdelivery of an RKM for registration of a BCAST service of a terminal toa BSM, under the control of the controller 1300. Herein, the RKM requestmessage may include an ID of the BCAST service and a content ID.

The transmitter 1302, upon receiving an RKM request response messagefrom the BSM unit in response to the RKM request message, transmits anLTKM request message for requesting delivery of an LTKM to be decryptedusing the RKM to the BSM. Herein, the LTKM may be provided to theterminal registered in the BCAST service. The RKM request responsemessage may include the ID of the BCAST service, the content ID, and theRKM, and the LTKM request response message may include the ID of theBCAST service, the content ID, and the LTKM.

The transmitter 1302, upon receiving an LTKM request response messagefrom the BSM unit in response to the LTKM request message, transmits anSTKM request message for requesting delivery of an STKM to be decryptedusing the LTKM to the BSM. Herein, the STKM may include a TEK used forthe terminal to encrypt the BCAST service, and the STKM request messagemay include the ID of the BCAST service and the content ID.

Each of the RKM, LTKM, and STKM request messages transmitted by thetransmitter 1302 may include, for example, information about a tagindicating a message type, a version of standard supported by a message,a message ID, an ID of the BSM corresponding to a message destinationID, an ID of the BSD/A unit corresponding to a message source ID, and atime when the message is transmitted.

Meanwhile, the receiver 1304 receives the RKM request response messagefrom the BSM unit after transmission of the RKM request message, andreceives the LTKM request response message from the BSM aftertransmission of the LTKM request message. The receiver 1304 receives theSTKM request response message from the BSM after transmission of theSTKM request message. Herein, the STKM request response message mayinclude the ID of the BCAST service, the content ID, and the STKM.

Each of the RKM, LTKM, and STKM request response messages received bythe receiver 1304 may include, for example, information about a tagindicating a message type, a version of standard supported by a message,a message ID, an ID of the BSD/A unit corresponding to a messagedestination ID, an ID of the BSM corresponding to a message source ID, atime when the message is transmitted, and status information indicatinga response result of the message.

Meanwhile, according to another embodiment of the present invention, thetransmitter 1302 and the receiver 1304 may perform the processes ofacquiring the RKM, the LTKM, and the STKM as shown in FIGS. 7B, 8B, and9B, under the control of the controller 1300.

The transmitter 1302, upon receiving an RKM delivery message fordelivery of the RKM from the BSM, transmits an RKM delivery confirmationmessage indicating success/failure in receipt of the RKM deliverymessage to the BSM. Herein, the RKM delivery message may include the IDof the BCAST service, the content ID, and the RKM, and the RKM deliveryconfirmation message may include the ID of the BCAST service and thecontent ID.

The transmitter 1302, upon receiving an LTKM delivery message fordelivery of the LTKM from the BSM after transmission of the RKM deliveryconfirmation message, transmits an RKM delivery confirmation messageindicating success/failure in receipt of the LTKM delivery message tothe BSM. Herein, the LTKM delivery message may include the ID of theBCAST service, the content ID, and the LTKM, and the LTKM deliveryconfirmation message may include the ID of the BCAST service and thecontent ID. The transmitter 1302, upon receiving an STKM deliverymessage for delivery of the STKM after transmission of the RKM deliveryconfirmation message, transmits an STKM delivery confirmation messageindicating success/failure in receipt of the STKM delivery message tothe BSM. Herein, the STKM delivery message may include the ID of theBCAST service, the content ID, and the STKM, and the STKM deliveryconfirmation message may include the ID of the BCAST service and thecontent ID.

Each of the above-described RKM, LTKM, and STKM delivery confirmationmessages transmitted by the transmitter 1302 may include informationabout a tag indicating a message type, a version of standard supportedby a message, a message ID, an ID of the BSM unit corresponding to amessage destination ID, an ID of the BSD/A corresponding to a messagesource ID, a time when the message is transmitted, and statusinformation indicating a response result of the message.

Meanwhile, the receiver 1304 receives each of the RKM, LTKM, and STKMdelivery messages. Herein, each of the RKM, LTKM, and STKM deliverymessages may include, for example, information about a tag indicating amessage type, a version of standard supported by a message, a messageID, an ID of the BSD/A corresponding to a message destination ID, an IDof the BSM corresponding to a message source ID, a time when the messageis transmitted, and a target terminal of the message.

Next, an internal configuration of the BSM according to an embodiment ofthe present invention will be described with reference to FIG. 14.

FIG. 14 is a block diagram of the BSM according to an exemplaryembodiment of the present invention.

Referring to FIG. 14, the BSM may include a controller 1400, atransmitter 1402, and a receiver 1404.

The controller 1400 controls the transmitter 1402 and the receiver 1404to perform the above-described operations of the BSM shown in FIGS. 3Aand 3B, 5A and 5B, 7A and 7B, 8A and 8B, and 9A and 9B.

For example, the transmitter 1402 and the receiver 1404 perform theprocesses of providing the RKM, the LTKM, and the STKM as shown in FIGS.7A, 8A, and 9A, under the control of the controller 1400.

The transmitter 1402, upon receiving an RKM request message forrequesting delivery of an RKM for registration of a BCAST service of aterminal from the BSD/A, transmits the RKM request response message tothe BSD/A. The RKM request response message may include the ID of theBCAST service, the content ID, and the RKM.

The transmitter 1402, upon receiving an LTKM request message forrequesting delivery of an LTKM to be decrypted using the RKM from theBSD/A unit after transmission of the RKM request response message,transmits an LTKM request response message to the BSD/A unit. The LTKMrequest response message may include the ID of the BCAST service, thecontent ID, and the LTKM.

The transmitter 1402, upon receiving an STKM request message forrequesting delivery of an STKM to be decrypted using the LTKM from theBSD/A unit after transmission of the LTKM request response message,transmits an STKM request response message to the BSD/A unit. The STKMrequest response message may include the ID of the BCAST service, thecontent ID, and the STKM.

The receiver 1404 receives each of the RKM request message, LTKM requestmessage, and STKM request message, which includes the ID of the BCASTservice, etc., from the BSD/A unit.

According to another embodiment of the present invention, thetransmitter 1402 and the receiver 1404 may perform the processes ofproviding the RKM, the LTKM, and the STKM as shown in FIGS. 7B, 8B, and9B, under the control of the controller 1400.

The transmitter 1402 transmits an RKM delivery message for delivery ofan RKM to a BCAST BSD/A. The transmitter 1402, upon receiving an RKMdelivery confirmation message indicating success/failure in receipt ofthe RKM delivery message from the BSD/A unit in response to the RKMdelivery message, transmits an LTKM delivery message for delivery of anLTKM to be decrypted using the RKM to the BSD/A.

Next, the transmitter 1402, upon receiving the LTKM deliveryconfirmation message in response to the LTKM delivery message from theBSD/A, transmits an STKM delivery message for delivery of an STKM to bedecrypted using the LTKM to the BSD/A unit.

The receiver 1404 receives the RKM delivery confirmation messageindicating success/failure in receipt of the RKM delivery message, theLTKM delivery confirmation message indicating success/failure in receiptof the LTKM delivery message, and the STKM delivery confirmation messageindicating success/failure in receipt of the STKM delivery message fromthe BSD/A unit.

While the invention has been shown and described with reference toexemplary embodiments thereof, it will be understood by those skilled inthe art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the invention as definedby the appended claims.

1. A broadcast (BCAST) Service Distribution/Adaptation (BSD/A) unit in amobile broadcast system providing a BCAST, comprising: a transmitter fortransmitting a Registration Key Material (RKM) request message forrequesting delivery of an RKM for registration of the BCAST service of aterminal to a BCAST Subscription Management (BSM) unit managingsubscriber information of the terminal; and a receiver for receiving anRKM request response message from the BSM unit, wherein the RKM requestmessage includes an identifier (ID) of the BCAST service, and the RKMrequest response message includes the ID of the BCAST service and theRKM, wherein the transmitter transmits a Long-Term Key Message (LTKM)request message for requesting delivery of an LTKM provided to theterminal during subscription of the BCAST service to the BSM unit,wherein the receiver receives an LTKM request response message from theBSM unit, wherein the LTKM request message includes the ID of the BCASTservice, and the LTKM request response message includes the ID of theBCAST service and the LTKM, wherein the transmitter transmits aShort-Term Key Message (STKM) request message for acquisition of an STKMincluding a Traffic Encryption Key (TEK) used for decryption of theBCAST service by the terminal to the BSM unit, wherein the receiverreceives an STKM request response message from the BSM unit, and whereinthe STKM request message includes the ID of the BCAST service, and theSTKM request response message includes the ID of the BCAST service andthe STKM.
 2. The BSD/A unit of claim 1, wherein each of the RKM, LTKM,STKM request messages includes information about a tag indicating amessage type, a version of standard supported by a message, a messageID, an ID of the BSM unit corresponding to a destination ID, an ID ofthe BSD/A unit corresponding to a source ID, and a time when the messageis transmitted.
 3. The BSD/A unit of claim 1, wherein each of the RKM,LTKM, STKM request response messages includes information about a tagindicating a message type, a version of standard supported by a message,a message ID, an ID of the BSD/A unit corresponding to a destination ID,an ID of the BSM unit corresponding to a source ID, a time when themessage is transmitted, and status information indicating a responseresult of the message.
 4. The BSD/A unit of claim 1, wherein each of theRKM request message, the RKM request response message, the LTKM requestmessage, the LTKM request response message, the STKM request message,and the STKM request response message further includes an ID of acontent.
 5. A broadcast (BCAST) Subscription Management (BSM) unit in amobile broadcast system providing a BCAST service, comprising: areceiver for receiving a Registration Key Material (RKM) request messagefor requesting delivery of an RKM for registration of a BCAST service ofa terminal, from a BCAST Service Distribution/Adaptation (BSD/A) unit;and a transmitter for transmitting an RKM request response message tothe BSD/A, wherein the RKM request message includes an identifier (ID)of the BCAST service, and the RKM request response message includes theID of the BCAST service and the RKM, wherein the receiver receives aLong-Term Key Message (LTKM) request message for requesting delivery ofan LTKM provided to the terminal during subscription of the BCASTservice, from the BSD/A unit, wherein the transmitter transmits an LTKMrequest response message to the BSD/A unit, wherein the LTKM requestmessage includes the ID of the BCAST service, and the LTKM requestresponse message includes the ID of the BCAST service and the LTKM,wherein the receiver receives a Short-Term Key Message (STKM) requestmessage for acquisition of an STKM including a Traffic Encryption Key(TEK) used for decryption of the BCAST service by the terminal, from theBSD/A unit, wherein the transmitter transmits an STKM request responsemessage to the BSD/A unit, and wherein the STKM request message includesthe ID of the BCAST service, and the STKM request response messageincludes the ID of the BCAST service and the STKM.
 6. The BSM unit ofclaim 5, wherein each of the RKM, LTKM, STKM request messages includesinformation about a tag indicating a message type, a version of standardsupported by a message, a message ID, an ID of the BSM unitcorresponding to a destination ID, an ID of the BSD/A unit correspondingto a source ID, and a time when the message is transmitted.
 7. The BSMunit of claim 5, wherein each of the RKM, LTKM, STKM request responsemessages includes information about a tag indicating a message type, aversion of standard supported by a message, a message ID, an ID of theBSD/A unit corresponding to a destination ID, an ID of the BSM unitcorresponding to a source ID, a time when the message is transmitted,and status information indicating a response result of the message. 8.The BSM unit of claim 5, wherein each of the RKM request message, theRKM request response message, the LTKM request message, the LTKM requestresponse message, the STKM request message, and the STKM requestresponse message further includes an ID of a content.
 9. A broadcast(BCAST) Subscription Management (BSM) unit in a mobile broadcast systemproviding a BCAST service, comprising: a transmitter for transmitting aRegistration Key Material (RKM) delivery message for delivery of an RKMfor registration of the BCAST service of a terminal to a BCAST ServiceDistribution/Adaptation (BSD/A) unit; and a receiver for receiving anRKM delivery confirmation message indicating success/failure in receiptof the RKM delivery message from the BSD/A unit, wherein the RKMdelivery message includes an identifier (ID) of the BCAST service andthe RKM, and the RKM delivery confirmation message includes the ID ofthe BCAST service, wherein the transmitter transmits a Long-Term KeyMessage (LTKM) delivery message for delivery an LTKM provided to theterminal during subscription of BCAST service to the BSD/A unit, whereinthe receiver receives an LTKM delivery confirmation message indicatingsuccess/failure in receipt of the LTKM delivery message, from the BSD/Aunit, wherein the LTKM delivery message includes the ID of the BCASTservice and the LTKM, and the LTKM delivery confirmation messageincludes the ID of the BCAST service, wherein the transmitter transmitsa Short-Term Key Message (STKM) delivery message for delivery an STKMincluding a Traffic Encryption Key (TEK) used for decryption of theBCAST service by the terminal to the BSD/A unit, wherein the receiverreceives an STKM delivery confirmation message indicatingsuccess/failure in receipt of the STKM delivery message from the BSD/Aunit, and wherein the STKM delivery message includes the ID of the BCASTservice and the STKM, and the STKM delivery confirmation messageincludes the ID of the BCAST service.
 10. The BSM unit of claim 9,wherein each of the RKM, LTKM, STKM delivery messages includesinformation about a tag indicating a message type, a version of standardsupported by a message, a message ID, an ID of the BSDA unitcorresponding to a destination ID, an ID of the BSM unit correspondingto a source ID, a time when the message is transmitted, and a targetterminal of the message.
 11. The BSM unit of claim 9, wherein each ofthe RKM, LTKM, STKM delivery confirmation messages includes informationabout a tag indicating a message type, a version of standard supportedby a message, a message ID, an ID of the BSM unit corresponding to adestination ID, an ID of the BSD/A unit corresponding to a source ID, atime when the message is transmitted, and a target terminal of themessage.
 12. The BSM unit of claim 9, wherein each of the RKM deliverymessage, the RKM delivery confirmation message, the LTKM deliverymessage, the LTKM delivery confirmation message, the STKM deliverymessage, and the STKM delivery confirmation message further includes anID of a content.
 13. A broadcast (BCAST) Service Distribution/Adaptation(BSD/A) unit in a mobile broadcast system providing a BCAST service,comprising: a receiver for receiving a Registration Key Material (RKM)delivery message for delivery of an RKM for registration of the BCASTservice of a terminal, from a BCAST Subscription Management (BSM) unit;and a transmitter for transmitting an RKM delivery confirmation messageindicating success/failure in receipt of the RKM delivery message, tothe BSM unit, wherein the RKM delivery message includes an identifier(ID) of the BCAST service, and the RKM, and the RKM deliveryconfirmation message includes the ID of the BCAST service, wherein thereceiver receives a Long-Term Key Message (LTKM) delivery message fordelivery an LTKM provided to the terminal during subscription of BCASTservice, from the BSM unit, wherein the transmitter transmits an LTKMdelivery confirmation message indicating success/failure in receipt ofthe LTKM delivery message, to the BSM unit, wherein the LTKM deliverymessage includes the ID of the BCAST service and the LTKM, and the LTKMdelivery confirmation message includes the ID of the BCAST service,wherein the receiver receives a Short-Term Key Message (STKM) deliverymessage for delivery an STKM including a Traffic Encryption Key (TEK)used for decryption of the BCAST service by the terminal, from the BSMunit, wherein the transmitter transmits an STKM delivery confirmationmessage indicating success/failure in receipt of the STKM deliverymessage to the BSM unit, and wherein the STKM delivery message includesthe ID of the BCAST service and the STKM, and the STKM deliveryconfirmation message includes the ID of the BCAST service.
 14. The BSD/Aunit of claim 13, wherein each of the RKM, LTKM, STKM delivery messagesincludes information about a tag indicating a message type, a version ofstandard supported by a message, a message ID, an ID of the BSDA unitcorresponding to a destination ID, an ID of the BSM unit correspondingto a source ID, a time when the message is transmitted, and a targetterminal of the message.
 15. The BSD/A unit of claim 13, wherein each ofthe RKM, LTKM, STKM delivery confirmation messages includes informationabout a tag indicating a message type, a version of standard supportedby a message, a message ID, an ID of the BSM unit corresponding to adestination ID, an ID of the BSD/A unit corresponding to a source ID, atime when the message is transmitted, and a target terminal of themessage.
 16. The BSD/A unit of claim 13, wherein each of the RKMdelivery message, the RKM delivery confirmation message, the LTKMdelivery message, the LTKM delivery confirmation message, the STKMdelivery message, and the STKM delivery confirmation message furtherincludes an ID of a content.
 17. A method for transmitting/receivingencryption information by a broadcast (BCAST) ServiceDistribution/Adaptation (BSD/A) unit in a mobile broadcast systemproviding a BCAST service, the method comprising: transmitting aRegistration Key Material (RKM) request message for requesting deliveryof an RKM for registration of the BCAST service of a terminal to a BCASTSubscription Management (BSM) unit managing subscriber information ofthe terminal; receiving an RKM request response message from the BSM;transmitting a Long-Term Key Message (LTKM) request message forrequesting delivery of an LTKM provided to the terminal duringsubscription of the BCAST service to the BSM unit; receiving an LTKMrequest response message from the BSM unit; transmitting a Short-TermKey Message (STKM) request message for acquisition of an STKM includinga Traffic Encryption Key (TEK) used for decryption of the BCAST serviceby the terminal to the BSM unit; and receiving an STKM request responsemessage from the BSM unit, wherein the RKM request message includes anidentifier (ID) of the BCAST service, and the RKM request responsemessage includes the ID of the BCAST service and the RKM, wherein theLTKM request message includes the ID of the BCAST service, and the LTKMrequest response message includes the ID of the BCAST service and theLTKM, and wherein the STKM request message includes the ID of the BCASTservice, and the STKM request response message includes the ID of theBCAST service and the STKM.
 18. The method of claim 17, wherein each ofthe RKM, LTKM, STKM request messages includes information about a tagindicating a message type, a version of standard supported by a message,a message ID, an ID of the BSM unit corresponding to a destination ID,an ID of the BSD/A unit corresponding to a source ID, and a time whenthe message is transmitted.
 19. The method of claim 17, wherein each ofthe RKM, LTKM, STKM request response messages includes information abouta tag indicating a message type, a version of standard supported by amessage, a message ID, an ID of the BSD/A unit corresponding to adestination ID, an ID of the BSM unit corresponding to a source ID, atime when the message is transmitted, and status information indicatinga response result of the message.
 20. The method of claim 17, whereineach of the RKM request message, the RKM request response message, theLTKM request message, the LTKM request response message, the STKMrequest message, and the STKM request response message further includesan ID of a content.
 21. A method for transmitting/receiving encryptioninformation by a broadcast (BCAST) Subscription Management (BSM) unit ina mobile broadcast system providing a BCAST service, the methodcomprising: receiving a Registration Key Material (RKM) request messagefor requesting delivery of an RKM for registration of the BCAST serviceof a terminal, from a BCAST Service Distribution/Adaptation (BSD/A)unit; transmitting an RKM request response message to the BSD/A;receiving a Long-Term Key Message (LTKM) request message for requestingdelivery of an LTKM provided to the terminal during subscription of theBCAST service, from the BSD/A unit; transmitting an LTKM requestresponse message to the BSD/A unit; receiving a Short-Term Key Message(STKM) request message for acquisition of an STKM including a TrafficEncryption Key (TEK) used for decryption of the BCAST service by theterminal, from the BSD/A unit; and transmitting an STKM request responsemessage to the BSD/A, wherein the RKM request message includes anidentifier (ID) of the BCAST service, and the RKM request responsemessage includes the ID of the BCAST service and the RKM, wherein theLTKM request message includes the ID of the BCAST service, and the LTKMrequest response message includes the ID of the BCAST service and theLTKM, and wherein the STKM request message includes the ID of the BCASTservice, and the STKM request response message includes the ID of theBCAST service and the STKM.
 22. The method of claim 21, wherein each ofthe RKM, LTKM, STKM request messages includes information about a tagindicating a message type, a version of standard supported by a message,a message ID, an ID of the BSM unit corresponding to a destination ID,an ID of the BSD/A unit corresponding to a source ID, and a time whenthe message is transmitted.
 23. The method of claim 21, wherein each ofthe RKM, LTKM, STKM request response messages includes information abouta tag indicating a message type, a version of standard supported by amessage, a message ID, an ID of the BSD/A unit corresponding to adestination ID, an ID of the BSM unit corresponding to a source ID, atime when the message is transmitted, and status information indicatinga response result of the message.
 24. The method of claim 21, whereineach of the RKM request message, the RKM request response message, theLTKM request message, the LTKM request response message, the STKMrequest message, and the STKM request response message further includesan ID of a content.
 25. A method for transmitting/receiving encryptioninformation by a broadcast (BCAST) Subscription Management (BSM) unit ina mobile broadcast system providing a BCAST service, the methodcomprising: transmitting a Registration Key Material (RKM) deliverymessage for delivery of an RKM for registration of the BCAST service ofa terminal to a BCAST Service Distribution/Adaptation (BSD/A) unit;receiving an RKM delivery confirmation message indicatingsuccess/failure in receipt of the RKM delivery message, from the BSD/Aunit; transmitting a Long-Term Key Message (LTKM) delivery message fordelivery an LTKM provided to the terminal during subscription of theBCAST service to the BSD/A unit; receiving an LTKM delivery confirmationmessage indicating success/failure in receipt of the RKM deliverymessage from the BSD/A unit; transmitting a Short-Term Key Message(STKM) delivery message for delivery an STKM including a TrafficEncryption Key (TEK) used for decryption of the BCAST service by theterminal to the BSD/A unit; and receiving an STKM delivery confirmationmessage indicating success/failure in receipt of the STKM deliverymessage from the BSD/A unit, wherein the RKM delivery message includesan identifier (ID) of the BCAST service and the RKM, and the RKMdelivery confirmation message includes the ID of the BCAST service,wherein the LTKM delivery message includes the ID of the BCAST serviceand the LTKM, and the LTKM delivery confirmation message includes the IDof the BCAST service, and wherein the STKM delivery message includes theID of the BCAST service and the STKM, and the STKM delivery confirmationmessage includes the ID of the BCAST service.
 26. The method of claim25, wherein each of the RKM, LTKM, STKM delivery messages includesinformation about a tag indicating a message type, a version of standardsupported by a message, a message ID, an ID of the BSD/A unitcorresponding to a destination ID, an ID of the BSM unit correspondingto a source ID, a time when the message is transmitted, and a targetterminal of the message.
 27. The method of claim 25, wherein each of theRKM, LTKM, STKM delivery confirmation messages includes informationabout a tag indicating a message type, a version of standard supportedby a message, a message ID, an ID of the BSM unit corresponding to adestination ID, an ID of the BSD/A unit corresponding to a source ID, atime when the message is transmitted, and status information indicatinga response result of the message.
 28. The method of claim 25, whereineach of the RKM delivery message, the RKM delivery confirmation message,the LTKM delivery message, the LTKM delivery confirmation message, theSTKM delivery message, and the STKM delivery confirmation messagefurther includes an ID of a content.
 29. A method fortransmitting/receiving encryption information by a broadcast (BCAST)Service Distribution/Adaptation (BSD/A) unit in a mobile broadcastsystem providing a BCAST service, the method comprising: receiving aRegistration Key Material (RKM) delivery message for delivery of an RKMfor registration of the BCAST service of a terminal, from a BCASTSubscription Management (BSM) unit; transmitting an RKM deliveryconfirmation message indicating success/failure in receipt of the RKMdelivery message, to the BSM unit; receiving a Long-Term Key Message(LTKM) delivery message for delivery an LTKM provided to the terminalduring subscription of the BCAST service, from the BSM unit;transmitting an LTKM delivery confirmation message indicatingsuccess/failure in receipt of the RKM delivery message, to the BSM unit;receiving a Short-Term Key Message (STKM) delivery message for deliveryan STKM including a Traffic Encryption Key (TEK) used for decryption ofthe BCAST service by the terminal, from the BSM unit; and transmittingan STKM delivery confirmation message indicating success/failure inreceipt of the STKM delivery message, to the BSM unit, wherein the RKMdelivery message includes an identifier (ID) of the BCAST service andthe RKM, and the RKM delivery confirmation message includes the ID ofthe BCAST service, wherein the LTKM delivery message includes the ID ofthe BCAST service and the LTKM, and the LTKM delivery confirmationmessage includes the ID of the BCAST service, and wherein the STKMdelivery message includes the ID of the BCAST service and the STKM, andthe STKM delivery confirmation message includes the ID of the BCASTservice.
 30. The method of claim 29, wherein each of the RKM, LTKM, STKMdelivery messages includes information about a tag indicating a messagetype, a version of standard supported by a message, a message ID, an IDof the BSD/A unit corresponding to a destination ID, an ID of the BSMunit corresponding to a source ID, a time when the message istransmitted, and a target terminal of the message.
 31. The method ofclaim 29, wherein each of the RKM, LTKM, STKM delivery confirmationmessages includes information about a tag indicating a message type, aversion of standard supported by a message, a message ID, an ID of theBSM unit corresponding to a destination ID, an ID of the BSD/A unitcorresponding to a source ID, a time when the message is transmitted,and status information indicating a response result of the message. 32.The method of claim 29, wherein each of the RKM delivery message, theRKM delivery confirmation message, the LTKM delivery message, the LTKMdelivery confirmation message, the STKM delivery message, and the STKMdelivery confirmation message further includes an ID of a content.